)The partition function for the helix-coil transition equilibrium is 

where "V" is the end vector formula_2, arranged to ensure the coil state of the first and last residues in the polymer.This strategy for parameterizing helix-coil transitions was originally developed for alpha helices, whose hydrogen bonds occur between residues "i" and "i+4"; however, it is straightforward to extend the model to 310 helices and pi helices, with "i+3" and "i+5" hydrogen bonding patterns respectively.